Identification of SNAIL1 Peptide-Based Irreversible Lysine-Specific Demethylase 1‑Selective Inactivators

Inhibition of lysine-specific demethylase 1 (LSD1), a flavin-dependent histone demethylase, has recently emerged as a new strategy for treating cancer and other diseases. LSD1 interacts physically with SNAIL1, a member of the SNAIL/SCRATCH family of transcription factors. This study describes the discovery of SNAIL1 peptide-based inactivators of LSD1. We designed and prepared SNAIL1 peptides bearing a propargyl amine, hydrazine, or phenylcyclopropane moiety. Among them, peptide <b>3</b>, bearing hydrazine, displayed the most potent LSD1-inhibitory activity in enzyme assays. Kinetic study and mass spectrometric analysis indicated that peptide <b>3</b> is a mechanism-based LSD1 inhibitor. Furthermore, peptides <b>37</b> and <b>38</b>, which consist of cell-membrane-permeable oligoarginine conjugated with peptide <b>3</b>, induced a dose-dependent increase of dimethylated Lys4 of histone H3 in HeLa cells, suggesting that they are likely to exhibit LSD1-inhibitory activity intracellularly. In addition, peptide <b>37</b> decreased the viability of HeLa cells. We believe this new approach for targeting LSD1 provides a basis for development of potent selective inhibitors and biological probes for LSD1

Triazole Ureas Act as Diacylglycerol Lipase Inhibitors and Prevent Fasting-Induced Refeeding

Triazole ureas constitute a versatile class of irreversible inhibitors that target serine hydrolases in both cells and animal models. We have previously reported that triazole ureas can act as selective and CNS-active inhibitors for diacylglycerol lipases (DAGLs), enzymes responsible for the biosynthesis of 2-arachidonoyl­glycerol (2-AG) that activates cannabinoid CB₁ receptor. Here, we report the enantio- and diastereoselective synthesis and structure–activity relationship studies. We found that 2,4-substituted triazole ureas with a biphenylmethanol group provided the most optimal scaffold. Introduction of a chiral ether substituent on the 5-position of the piperidine ring provided ultrapotent inhibitor <b>38</b> (DH376) with picomolar activity. Compound <b>38</b> temporarily reduces fasting-induced refeeding of mice, thereby emulating the effect of cannabinoid CB₁-receptor inverse agonists. This was mirrored by <b>39</b> (DO34) but also by the negative control compound <b>40</b> (DO53) (which does not inhibit DAGL), which indicates the triazole ureas may affect the energy balance in mice through multiple molecular targets

In Vitro and in Vivo Evaluation of ¹¹C‑Labeled Azetidinecarboxylates for Imaging Monoacylglycerol Lipase by PET Imaging Studies

Monoacylglycerol lipase (MAGL) is the principle enzyme for metabolizing endogenous cannabinoid ligand 2-arachidonoyglycerol (2-AG). Blockade of MAGL increases 2-AG levels, resulting in subsequent activation of the endocannabinoid system, and has emerged as a novel therapeutic strategy to treat drug addiction, inflammation, and neurodegenerative diseases. Herein we report a new series of MAGL inhibitors, which were radiolabeled by site-specific labeling technologies, including ¹¹C-carbonylation and spirocyclic iodonium ylide (SCIDY) radiofluorination. The lead compound [¹¹C]<b>10</b> (MAGL-0519) demonstrated high specific binding and selectivity in vitro and in vivo. We also observed unexpected washout kinetics with these irreversible radiotracers, in which in vivo evidence for turnover of the covalent residue was unveiled between MAGL and azetidine carboxylates. This work may lead to new directions for drug discovery and PET tracer development based on azetidine carboxylate inhibitor scaffold

In Vitro and in Vivo Evaluation of ¹¹C‑Labeled Azetidinecarboxylates for Imaging Monoacylglycerol Lipase by PET Imaging Studies

Monoacylglycerol lipase (MAGL) is the principle enzyme for metabolizing endogenous cannabinoid ligand 2-arachidonoyglycerol (2-AG). Blockade of MAGL increases 2-AG levels, resulting in subsequent activation of the endocannabinoid system, and has emerged as a novel therapeutic strategy to treat drug addiction, inflammation, and neurodegenerative diseases. Herein we report a new series of MAGL inhibitors, which were radiolabeled by site-specific labeling technologies, including ¹¹C-carbonylation and spirocyclic iodonium ylide (SCIDY) radiofluorination. The lead compound [¹¹C]<b>10</b> (MAGL-0519) demonstrated high specific binding and selectivity in vitro and in vivo. We also observed unexpected washout kinetics with these irreversible radiotracers, in which in vivo evidence for turnover of the covalent residue was unveiled between MAGL and azetidine carboxylates. This work may lead to new directions for drug discovery and PET tracer development based on azetidine carboxylate inhibitor scaffold

In Vitro and in Vivo Evaluation of ¹¹C‑Labeled Azetidinecarboxylates for Imaging Monoacylglycerol Lipase by PET Imaging Studies

Monoacylglycerol lipase (MAGL) is the principle enzyme for metabolizing endogenous cannabinoid ligand 2-arachidonoyglycerol (2-AG). Blockade of MAGL increases 2-AG levels, resulting in subsequent activation of the endocannabinoid system, and has emerged as a novel therapeutic strategy to treat drug addiction, inflammation, and neurodegenerative diseases. Herein we report a new series of MAGL inhibitors, which were radiolabeled by site-specific labeling technologies, including ¹¹C-carbonylation and spirocyclic iodonium ylide (SCIDY) radiofluorination. The lead compound [¹¹C]<b>10</b> (MAGL-0519) demonstrated high specific binding and selectivity in vitro and in vivo. We also observed unexpected washout kinetics with these irreversible radiotracers, in which in vivo evidence for turnover of the covalent residue was unveiled between MAGL and azetidine carboxylates. This work may lead to new directions for drug discovery and PET tracer development based on azetidine carboxylate inhibitor scaffold